Electrical current passing through the ignitor operates a small heater that ‘warps’ an internal piece of bimetal to open the gas

valve. As long as the burner flame continues to heat the ignitor, its electrical resistance remains low enough to keep the valve turned on. If, for any reason, the flame is extinguished, the igniter's resistance increases and the valve turns off the gas to the burner.

While the valves are very reliable, the igniters have become the most common parts failure on these systems. Which is to be expected, I guess; they’re doing their job in a gas flame!

Igniters come in two basic types, ‘flat’ and ‘round’, seen below, and they can’t be interchanged.

The 'Flat Style', # IGN5

A Round One, # AR403

Each type operates at a particular amperage level, and is matched to the type gas valve it operates. The stainless steel ‘cages’ that protect them usually correspond to their actual shape, which helps you figure out which one yours uses. And to make it even easier, there’s pretty much only One round one that fits them all. Flat ones vary only in the length of the ceramic block to which they’re mounted. Electrically they’re nearly all the same.

While it’s possible to diagnose one of these systems using an ammeter, it usually isn’t necessary. Since I try to keep life simple, and since these igniters have really dropped in price the last few years, it’s pretty easy to figure out what’s up with your cold oven.

If your oven doesn’t light, but you see the ignitor glowing, it will most likely be glowing a very dull red and not drawing enough current to operate the valve. Or, in some cases, it will operate the valve very slightly and you’ll smell some gas odor. Neither case is desirable or acceptable!

Watch a clock or stopwatch. If it takes more than 2 minutes to light, you’ll want to replace the ignitor; it’s the culprit in 90% of these. And this is the best way for you to diagnose your ignition system! In most cases, that’s all there is to it. You don’t even have to worry about wire polarity on the new ignitor – they can be wired either way. Just be sure it’s wired like the old one, and not connected to 120V directly, or it will burn out.Ignitor and valve must be in series with each other, or you’ll burn out one or both, fast!

If you’ve replaced the ignitor and it glows but the oven still doesn’t light, it’s time for a new valve. They’re pricier, but I usually recommend doing this once in a range’s life if necessary. Still much cheaper than a new range.

If there’s no ‘glow’ at all, take a close look at the ignitor, and you’ll often see a crack, or it may even be obvious that it’s broken apart.

You can use an ohmmeter to test for continuity if no cracks are visible.

Just be sure to power the range down. In some models, one side of the oven valve is always ‘hot’ with respect to ground, like some electric range bake element terminals.

New igniters ship with two ceramic wire nuts, and you simply connect the new part’s wires to the originals, using the original plug if yours has one.

A bit of hi-temp. grease on the mounting screws will be a big help if you have to repeat this job in the future. These screws are subject to very high heating, and can ‘freeze’ into their threads so tightly you’d like to blast to get them out sometimes.

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It doesn't work at allNo powerMake sure there's power getting to your range, oven or cooktop. Check for a tripped circuit breaker or a blown fuse. Check the wall socket for power with a voltmeter or by plugging something else in.

Top burner doesn't workA lot of times the problem is with a dirty or a clogged burner. Make sure the burner is clean.

If you have a pilotless model, it uses a spark igniter to ignite the gas, which works in a combination with a spark switch (located on the burner gas valve) and a spark module. Because it is not simple to test these parts and find out which one is defective, we recommend to contact a professional appliance technician.

It doesn't bakeBake igniterWhen the bake igniter becomes weak or burns out, your oven would not bake. The bake igniter is usually mounted on the oven burner. It's about 1 inch by 4-8 inches (depending on the model), and comes in round or flat styles. If you don't see the igniter glow at all, it's probably burned out. Replace the igniter if found defective. Note: one of the exceptions could be that your oven is set to automatic mode instead of manual. If this is the case, set your oven to manual mode and check again.

If the bake igniter glows red and not bright yellow or white, it is probably because it is too weak. When this happens, the safety valve would not let the gas out into the oven burner. A weak igniter must be replaced.

A faulty igniter is probably the most common cause, however there are others:

It doesn't broilBroil igniterWhen the broil igniter becomes weak or burns out, your oven would not broil. The broil igniter is usually mounted on the oven burner. It's about 1 inch by 4-8 inches (depending on the model), and comes in round or flat styles. If you don't see the igniter glow at all, it's probably burned out. Replace the igniter if found defective. Note: one of the exceptions could be that your oven is set to automatic mode instead of manual. If this is the case, set your oven to manual mode and check again.

If the broil igniter glows red and not bright yellow or white, it is probably because it is too weak. When this happens, the safety valve would not let the gas out into the oven burner. A weak igniter must be replaced.

A faulty igniter is probably the most common cause, however there are others:

A common thing with weak ignitors is a stronger than normal smell of gas ,plus the oven vents into the room,an exhaust fan is recommended whenever baking,the top burners can be lit with out power but the oven cannot the ignitors are like a safety if they lose power the gas valve to the oven will shut off,when either of the ignitors are lit it will take approx 30-45 seconds for the valve to open and gas to flow,if it is taking 2-3minutes or more then the ignitor is weak,you can have them checked out 3.2 -3.6 amps is good ,anything below that they are weak and need replacing.--------

The igniter can be bad even if it glows. You have to measure the current drawn by the igniter. If it's 3.2 amps or less then the igniter is the culprit.